Particle-filled fiber and articles formed from the same

ABSTRACT

A melt-spun polymer fiber is provided having a cross-section and a length. A detectable particulate has a size of less than 31 microns and present in an amount of 2.0 to 50.0 weight percent loadings of metal or 10 to 80 weight percent loadings of radiopaque particles to render the polymer fiber detectable by metal (magnetic) or X-ray detection, alone or in combination with a secondary functional particulate distributed in or on the polymer fiber to render the polymer fiber chemically responsive to a chemical reactant, change in pH or temperature. The detectable particulate and the secondary functional particulate are each independently present in a core, a sheath, or both portions of polymer matrix. A process of detecting a fabric made from such a fiber. The fabric article passes through detector. A signal is collected from the detector indicative of the presence of the fabric article.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application that claims prioritybenefit of U.S. Provisional Application Ser. No. 62/029,063, filed Jul.25, 2014, the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to the technical field of polymericcomposite fibers, and in particular to polymeric fibers with highloadings of functional particulate that impart specific physical,mechanical or chemical properties to the articles formed from suchfibers.

BACKGROUND OF THE INVENTION

Many industries have a need for functional polymers and articles madetherefrom. By way of example, a food, medical, or pharmaceuticalproduction line maintains tight audit control of service articles thatenter the medical or manufacturing facility to assure such articles donot accidently enter the process or production stream as a contaminantthat can be fragmented into dangerous shards. Historically, plasticshave been precluded from some environments due to the inability tolocate such articles with product screening metal or X-ray detectors.Recently, plastic articles have been developed that are filled withmetal particulate or barium sulfate, as detailed US Patent ApplicationPublication US20120241589 that are detectable with magnetic or X-raydetectors, yet still process as injection moldable thermoplastics andoperate in manner similar to their unfilled conventional counterparts.

By way of example, U.S. Pat. No. 5,897,673 teaches fibers containingfine metallic particles that are cross-linked to the polymeric fiber.While various pure metals are contemplated in the literature, littleattention has been paid to the unique problems associated with stainlesssteel particulate or other functional particulates. As many manufacturedsubstances can only be exposed to stainless steel or other functionalparticulates, the lack of stainless steel or other functional particlefilled fibers precludes the usage of many useful articles from thesecontrolled manufacturing sites. By way of example various wipes, haircovers, suits, aprons and shoe covers and other manufacturing aids orpersonal protective equipment if made from stainless steel or otherfunctional particulates containing fibers could allow better qualitycontrol of manufacturing with less stringent audit processes, as anysuch articles lost in a production stream could be detected by X-ray ormagnetic anomaly. However, injection molded parts containing loading ofmetals or electron dense substances needed for detection are limiting interms of the materials that can be formed.

Thus, there exists a need for a spun thermoplastic fiber filled withparticulate, the particulate rendering a resultant non-woven articleeither detectable in a production context alone or also to includeadditional functional particulate. There also exists a need for suchfibers that process and retain properties of conventional thermoplasticfibers to promote production of various articles from fibers that havethe added benefit of imparting functional properties while operating ina manner similar to conventional articles.

SUMMARY OF THE INVENTION

A melt-spun polymer fiber is provided having a cross-section and alength. A detectable particulate has a size of less than 31 microns andpresent in an amount of 2 to 50 total weight percent metal particulateto render the polymer fiber detectable by magnetic detection or 10 to 80total weight percent radiopaque particulate to render the polymer fiberdetectable by X-ray detection, alone or in combination with a secondaryfunctional particulate distributed in or on the polymer fiber to renderthe polymer fiber chemically responsive to a chemical reactant, changein pH or temperature. The detectable particulate and the secondaryfunctional particulate are each independently present in a core, asheath, or both portions of polymer matrix. A process of detecting afabric made from such a fiber is provided. The fabric article passesthrough detector. A signal is collected from the detector indicative ofthe presence of the fabric article.

A particle filled spun fiber that when formed into a nonwoven materialaffords an article that is detectable so as to prevent retention in amedical or production context. The resultant article is also renderedfunctional through the inclusion of additional types of particulate.Non-woven fabrics are formed that have additional functionality in thecontext of filtration; blood clotting; detection of changes in pH,temperature, of the presence of a chemical or biologic; or can besolidified to form a form fitting mass. In a prototypical form sheets inparticle filled non-woven fibers are formed as wipes for various wipingapplications such as personal hygiene, medical procedures, or equipmentor parts cleaning. The present invention may also be used to manufacturevarious personal protective articles from such sheets such as shoecovers, hair nets, beard nets, sleeve covers, aprons or any otherprotective article that can be used in the food, medical,pharmaceutical, or other industries where there is a concern regardingthe need for specific physical, chemical, or mechanical properties. Thematerial may also be used to manufacture other materials illustrativelyincluding filters and filter media and electrostatically dissipativeproducts.

A detectable particulate-containing article afford the benefit ofsubsequent detection and inventory control to an otherwise conventionalarticle, and with the addition of functional particulate materialincluded in the fiber affords functionality unique to various fields ofendeavor. Detectable particulate additives are present from 2.0 to 50.0weight percent loadings of metal or 10 to 80 weight percent loadings ofradiopaque particles in the melt-spun fiber, for manufacturing thefilled-fiber non-woven material. This is accomplished by incorporatingdetectable particles with a size of D90<31 micron or smaller into amonofilament, composite or bi-, tri-, or multi-component fiber in thespinning process. A secondary, functional particulate is added during orafter the spinning process to impart additional functionality to theresulting non-woven article. One feature of the functional fibers isthat a constituent of the composite or multi-component fiber is aremovable sheath that upon removal exposes the underlying particles. Thenovel feature is that processing, cleaning, protective, or othernon-woven articles formed with fibers containing the above referenceddetectable particulate alone, or in combination with functionaladditives are used to impart detectability, as well as specificfunctional properties associated with the inclusion of secondary,functional particulate.

A fiber is provided with a polymer having a cross-section and a length.A particulate is distributed in the polymer in an amount to make thefiber detectable alone, or also functional. The particulate is presentin a core, a sheath, or both portions of the fiber defined by a polymermatrix.

A process of detecting a fabric article is provided that includes theformation of a fiber in the form of a polymer having a cross-section anda length. A particulate is distributed in the polymer. A fiber is formedinto a non-woven fabric. A fabric article may then be manufactured fromthe fabric. The fabric article provides an end-use functionality. Asignal is collected from the X-ray detector or the magnetic detectorindicative of the presence of the fabric article.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further detailed with respect to the followingfigures that depict various aspects of the present invention.

FIGS. 1A-1C: FIG. 1A shows conventional prior art 100% polypropylene(PP) fibers; FIG. 1B shows an optical micrograph of meltblownpolypropylene fiber containing 30.0 wt % barium sulfate particles at500× magnification in accordance with embodiments of the invention; FIG.1C shows UV micrographs of extruded (meltspun without drawing)polypropylene fiber containing 30.0 wt % barium sulfate particles at200× magnification in accordance with embodiments of the invention.

FIGS. 2A-2H are fiber photographs and their corresponding X-ray films:Photograph of extruded polypropylene fiber containing 30.0 wt % bariumsulfate particles (FIG. 2A), X-ray film of extruded polypropylene fibercontaining 30.0 wt % barium sulfate particles (FIG. 2B), photograph ofpad cut from meltblown polypropylene fiber containing 30.0 wt % bariumsulfate particles (FIG. 2C), X-ray film of pad cut from meltblownpolypropylene fiber containing 30.0 wt % barium sulfate particles (FIG.2D), X-ray transmission images of barium sulfate/propylene meltblownpads clockwise from the first quadrant for 3, 6, 20, and 10 layers thatare produced with higher die temperature to yield a comparatively denserpad, as compared to those of FIG. 2F (FIG. 2E), X-ray transmissionimages of barium sulfate/propylene meltblown pads clockwise from thefirst quadrant for 3, 6, 20, and 10 layers that are produced with lowerdie temperature to yield a fluffier pad (FIG. 2F), X-ray transmissionimage of barium sulfate/propylene meltblown as a 10 layer pad submergedin 3.5 inches of water to simulate tissue with a US quarter used as aweight to keep the pad submerged (FIG. 2G), and X-ray transmission imageof barium sulfate/propylene meltblown as a 20 layer pad submerged in 3.5inches of water to simulate tissue with two US quarters used as a weightto keep the pad submerged (FIG. 2H).

DETAILED DESCRIPTION OF THE INVENTION

The present invention has utility as non-woven article formed from afiber that is electromagnetic spectrally detectable that may also havefunctional properties that are suitable for usage in a variety of fieldsand production environments illustratively including food production,medical, and pharmaceutical production environments. Through inclusionof a secondary functional particulate, an additional functionality isimparted to the resulting article. Such functionality includes drugdelivery; filtration; blood clotting; detection of changes in pH,temperature, of the presence of a chemical or biologic; or can besolidified to form a form fitting mass. In one aspect of the presentinvention it is possible to spin both PP and PET metal detectable fibersin the range of 2.0 denier per filament. This is accentuated by the factthat the inclusion of dense metal particles into the fiber “skews” thedenier count. Since denier is a weight per unit length measurement, itis possible to obtain fibers that are smaller in diameter than the samedenier pure polymer fibers.

As used herein, the term “fiber” defines both fibers of finite length,illustratively including conventional preselected length fiber, as wellas substantially continuous structures, such as continuous filaments,unless otherwise indicated. The fibers of the present invention areappreciated to be hollow or solid fibers, and further can have asubstantially round or circular cross-section or cross-sections ofdifferent symmetry space groups with other cross-sections illustrativelyincluding oval; circular; multi-lobal; lobular; and polygonal such astriangular, square, rectangular, trapezoidal, pentagonal, and hexagonal.An article of the present invention in some embodiments has a sheaththat varies in polymer or particulate, with the variation being as tocomposition or concentration, or both such properties.

As used herein, the term “multi-component fibers” is defined to includepreselected length fiber and continuous filaments with two or morediscrete structured domains of deliberately different composition orcomponent concentration and is intended to specifically includesheath/core and island configurations.

As used herein, the term “yarn” defines multiple fibers wound togetherinto a single continuous strand.

It is to be understood that in instances where a range of values areprovided that the range is intended to encompass not only the end pointvalues of the range but also intermediate values of the range asexplicitly being included within the range and varying by the lastsignificant figure of the range. By way of example, a recited range offrom 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

It is appreciated that both the cross-sectional shape of the fiber andthe configuration of the particulate and other components thereindepends upon the equipment that is used in the preparation of the fiber,the process conditions, and the melt viscosities of the variouscomponents. A wide variety of fiber configurations are readily producedaccording to the present invention to achieve loadings sufficient formetal or X-ray detection. Generally, as illustrated in the figures, afiber according to the present invention is a single or multi-componentcomposite fiber formed from a melt of one or more polymeric materialsloaded with one or more metallic or radiopaque materials as specifiedbelow.

The polymeric component of an inventive fiber is readily selected fromany of the types of polymers known in the art that are capable of beingformed into fibers, including polyolefins, polyvinyl, polyvinyl alcohol,polyesters, polyamides, co-polymers containing any of the aforementionedpolymers as blocks of a copolymer, and combinations thereof. Specificpolyolefins operative herein illustratively include polypropylene;polyethylene; polybutene; and polyisobutylene; polyamides such as NYLON6 and NYLON 6,6; polyacrylates; polystyrenes; polyurethanes; acetalresins; polyethylene vinyl alcohol; polyesters illustratively includingpolyethylene terephthalate (PET), polyethylene naphthalate,polytrimethylene terephthalate, poly(1,4-cyclohexylene dimethyleneterephthalate) (PCT), polycarbonates; and aliphatic polyestersillustratively including polylactic acid (PLA); polyphenylene sulfide;thermoplastic elastomers; polyacrylonitrile; cellulose and cellulosederivatives; polyaramids; acetals; fluoropolymers; copolymers andterpolymers thereof, and mixtures or blends thereof, and without regardas whether a given polyolefin is syndiotacic, eutectic, isotactic, oratactic.

Specific examples of aliphatic polyesters operative in the presentinvention include fiber forming polymers formed from a combination of analiphatic glycol such as ethylene glycol, propylene glycol, butyleneglycol, hexanediol, octanediol or decanediol or an oligomer of ethyleneglycol (e.g., diethylene glycol or triethylene glycol) with an aliphaticdicarboxylic acid such as succinic acid, adipic acid, hexanedicarboxylicacid or decaneolicarboxylic acid; or the self-condensation of hydroxycarboxylic acids other than poly(lactic acid), such as polyhydroxybutyrate, polyethylene adipate, polybutylene adipate, polyhexaneadipate, and copolymers containing the same. Aromatic polyestersoperative in the present invention include fiber forming polymers formedfrom polyesters of alkylene glycols having 2-10 carbon atoms andaromatic diacids; polyalkylene naphthalates, which are polyesters of2,6-naphthalenedicarboxylic acid and alkylene glycols, as for examplepolyethylene naphthalate; or polyesters derived from1,4-cyclohexanedimethanol and terephthalic acid, as for examplepolycyclohexane terephthalate. Exemplary polyalkylene terephthalatesinclude polyethylene terephthalate (also PET) and polybutyleneterephthalate.

In some inventive embodiments that are compliant with food, medical andpharmaceutical processing standards, the particulate is stainless steel.Other compositions of particulate to render an inventive fiber magneticor X-ray signal detectable include iron, bronze, brass, steel, bariumsalts, cobalt, titanium, tin, copper, tungsten, platinum, silver,bismuth, zinc, lead, molybdenum, neodymium-iron, samarium-cobalt, alloysof any of the aforementioned, oxides of any of the aforementionedmetals, and nitrides of any of the aforementioned. It is appreciatedthat cobalt alloys such as cobalt-samarium, and neodymium alloys haveexceptionally high magnetic moments that allow for magnetic detection atlower weight loading compared for ferrite. In some inventiveembodiments, the stainless steel is ferromagnetic and detectable bymagnetic induction coil detectors. Specific grades of stainlessparticulate operative herein include 300 series, 400 series and inparticular 306 (L), 316 and 430 compositions. It is appreciated that inaddition to spherical particulate shown in FIGS. 1B and 1C; prolatespheroids, oblate spheroids, and cylindrical rods of the particulate areused in the present invention. It has been surprisingly discovered thatnon-spherical particulate tends to align along a fiber length with theshortest linear dimension axis from the three orthogonal axes of X-Y-Zoriented generally perpendicular to the longest axis length of thefiber.

The present invention attempts to retain the processing and performanceproperties of the native polymer while imparting the ability to renderthe fiber and articles formed therefrom X-ray or magnetic anomalydetectable. This is achieved by inclusion of particulate having ashortest linear dimension, as measured from among the three orthogonalCartesian coordinate axes X-Y-Z that is less than or equal to one halfthe fiber cross-sectional average dimension along the three orthogonalCartesian coordinate axes X-Y-Z. For the purposes of calculation of theparticulate dimension, the average particle dimension is used forpolydisperse particulate. The detectable particulate with a size ofD90<31 micron or smaller. By way of example, a circular cross-sectionfiber with a diameter of 35 microns is loaded with spherical particulatehaving a diameter of less or equal to 17 microns. In some inventiveembodiments containing cylindrical rod particulate, the ratio of rodlength to diameter is between 1.3-20:1 and in still other embodimentsbetween 1.5-8:1

In certain embodiments, each of the polymeric components of an inventivefiber includes other substances known conventionally to modify aprocessing property or performance property. Such additive substancesillustratively include antioxidants, stabilizers, surfactants, waxes,flow promoters, solid solvents, dyes, pigments, plasticizers, andcombinations thereof. It is appreciated that a pigment can encompass acomposition of a particulate material detailed above to impartdetectability to the inventive fiber, and in such instances the pigmentis compositionally distinct from the particulate and present in a lowerweight percentage than the particulate.

It is appreciated that the loading of particulate to achieve X-ray ormagnetic detection of articles formed from inventive fibers is dictatedby factors including the X-ray cross-section or the magneticsusceptibility of a given particulate. Generally, ferromagneticmaterials are detectable at loadings of from >2 total weight percent bymagnetic induction detection. In those embodiments when theferromagnetic material is a rare earth magnet, typical loadings are from2 to 4 total weight percent for magnetic induction detection. Inspecific embodiments, where the particulate is magnetic stainless steelor any other electromagnetic spectrally detectable particulate, typicalloadings are from 2 to 50 total weight percent. It is appreciated thatthe above typical loading can be exceeded, yet often at the expense ofdetrimentally influencing the ability to process or increasing materialfinancial costs with only incremental improvements in detection.

Specific embodiments of the invention incorporate secondary functionaladditives into the manufacture of nonwoven materials, which allow forthe particulate-containing article to be used in a manner making benefitof the functional particulate material included in the fiber.Embodiments of the invention incorporate functional additive particulateat 0.01 to 5.0 weight percent loadings in the melt-spun fiber, for themanufacturing the filled-fiber material to be used in various functionalapplications. One feature of the functional fibers is that a constituentof the composite or multi-component fiber is removable to expose theparticles thereby imparting specific functionality. The novel feature isthat processing, cleaning, and protective articles formed with fiberscontaining the above referenced functional additives may be used toimpart specific functional properties.

Non limiting examples of uses for the functional particles may includethe delivery of blood clotting chemicals or other topical medicines, andcolor changing particles for indicating changes in pH and temperature,as well as detection and identification of specific chemicals, virus,and bacteria. Temperature change is readily detected with plasmonicnanoparticles able to change perceived color including metalnanoparticles, alone or in combination with oxide shells thatillustratively include gold, silver, and nickel. Oxide coatingsoperative herein illustratively include silica and iron oxide. It isappreciated that some of these secondary functional particles have asmall signal in electromagnetic spectrally detectable instrumentation incomparison to the detectable particulate. pH change is readily detectedqualitatively through incorporation of a pH indicator dye such asphenolphthalein impregnated into a paper or cellulosic particulate.Blood clotting particles include deformable microgel particles that areabout 1 micron in diameter and similar to the size of platelets, themicrogel particles being attached to human antibody fragments thatrecognize fibrin. Drug delivery is achieved with particlesillustratively including poly-lactic-co-glycolic acid (PLGA), metalnanocrystals; silica or dendrimers. Particles having a size of between 2nm and 5 microns are particularly well-suited for drug delivery.

Functional particles may also have reactive properties. Non limitingexamples of reactive particles may be particles that undergo anendothermic or exothermic reaction upon exposure to air andillustratively include iron particles. It is appreciated that based onthe temperature generated and the melt properties of the coupled fiber,can induce fusion between contiguous fibers. In other embodiments, theparticles are reacted with reagents that induce covalent bonding betweenparticles. By way of example metal particles are readily joined throughdisulfides; dicarboxylates; polycarboxylates such are acrylates;diamines; polyamines such as cyclen; or combinations thereof. As aresult, an inventive particle filled fiber mass is solidified byexposure to such a reagent. The resultant solidified fiber mass isuseful in a variety of applications including filtration, leaktreatment, or blood clotting. Non-limiting examples of filtrationapplications illustratively include water purification, bacteria,viruses, detrimental water-borne chemicals, and separation of metalfines. Further non-limiting example applications of the inventivereactive particles may include solar energy generation, addition ofabrasiveness or to deliver and apply a polish, and reactive particlesthat change colors or shape with induction of electricity.

In order to manufacture fibers of the present invention, particles arecompounded with one or more suitable pre-polymeric or polymericcompounds, as defined above that will form the basic fiber structure.The compounded material then undergoes a melt-spinning process and formsmetal/polymer composite fibers. Without intending to be bound to aparticular theory, the melt-spinning process tends to align asymmetricparticles with the shortest linear dimension axis along the direction offiber draw. In particular inventive embodiments, the particulate formsprotrusions extending from the sides of the fibers, as seen in FIGS.1B-1C. These protrusions have the added benefit of increase fibersurface area for a given length of fiber, and also appear to increasethe energy needed to pull contiguous fibers from one another. Withadjustment of melt temperature and draw rates, and in some instancesmodification of additive substances, inventive fibers are produced thathave a homogenous distribution of particulate along the length of thefiber and retain 70% of the tensile strength of a given fibercomposition absent particulate loading. In some embodiments a sheath issimultaneously drawn about a core. In still other embodiments, thesheath is free of particulate and the core is loaded with particulate.After extrusion, the fibers are drawn using technology known to thoseexperienced in the art to their final tensile strength and diameter,preferably between 0.1 and 500 microns in diameter. In otherembodiments, the fibers have a diameter of between 10 and 50 microns.

It has been surprisingly found that contrary to initial expectations,thermoplastic pellets loaded to up to 50 total weight percent of metalsand up to 80 total weight percent of radiopaque particulate in spite ofbeing more dense than non-particulate loaded thermoplastic pellets, aremelt-spun without adjusting the feeding system, with the proviso thatmagnets conventional to the melt-spinning equipment are removed in thoseinstances when the detected particulate is magnetic. Without intendingto be bound to a particular theory, it is believed that the thermalretention of the particulate affects the filament cool down and drawbehavior. Secondary functional particulate that is tolerant of thetemperature and pressure conditions conventional to melt-spun fiberproduction are readily intermixed with the detectable particulate andincorporated into a fiber therewith into a fiber core, fiber sheath, orboth.

While most polymers are more stable in the spinning process when onlymoderate draw force is applied, it has been surprisingly found that fora stock of particulate loaded pellets, applying higher draw forceresulted in drip free spinning behavior.

Generally, for melt-spinning multi-component composite fibers, at leasttwo polymers are extruded separately and fed into a polymer distributionsystem wherein the polymers are introduced into a spinneret plate. Inthe present invention, the particulate and at least one polymer aremixed or blended prior to extrusion using known techniques intoextrudable pellets. In such inventive embodiments, the particulate ishomogeneously dispersed throughout the polymer in which it is dispersedas the polymer streams are fed into the spinneret plate. It isappreciated that a particulate loaded pellets are used as a feedstockalone or intermixed with non-loaded pellets or pellets that vary in atleast property of polymer composition, particulate size, particulatecomposition, additive composition, additive loading, particulateloading, or a combination of such properties. The polymers followseparate paths to the fiber spinneret and are combined in a spinnerethole. The spinneret is configured so that the extrudant has the desiredoverall fiber cross-section. In a prototypical, multi-componentcomposite fiber according to the present invention, a core is extrudedfrom particulate loaded pellets with a sheath formed from a particulatefree pellet feedstock.

Following extrusion through the die, the resulting thin fluid strands,or filaments, remain in the molten state for some distance before theyare solidified by cooling in a surrounding fluid medium, which may be,for example, chilled air blown through the strands. Secondary functionalparticulate is in some inventive embodiments applied to fibers as anaerosol in the chilled air carrier used to cool the spun fiber. Oncesolidified, the filaments are taken up on a godet roller or anothertake-up surface. Secondary functional particulate is in some inventiveembodiments applied to fibers from a bath prior to, or after take up ongodet roller or other surface. In a continuous filament process, thestrands can be taken up on a godet which draws down the thin fluidstreams in proportion to the speed of the take-up godet. In a spun-bondprocess, the strands can be collected in a jet, such as for example, anair attenuator, and blown onto a take-up surface such as a roller or amoving belt to form a spun-bonded web. In a melt-blown process, air isejected at the surface of the spinneret which serves to simultaneouslydraw down and cool the thin fluid streams as they are deposited on atake-up surface in the path of cooling air, thereby forming a fiber web.Secondary functional particulate is in some inventive embodimentsapplied to spun-bonded web or a fiber web from an aerosol spray or asoaking bath.

Regardless of the type of melt spinning procedure used, generally thethin fluid streams are melt drawn down in a plastic state to orient thepolymer molecules for good tenacity. Typical melt draw down ratios knownin the industry are operative herein. In instances employing continuousfilament or staple processes, in certain embodiments, the strands aredrawn in the solid state with conventional drawing equipment, such as,for example, sequential godets operating at differential speeds.

Following drawing in the solid state, the continuous filaments incertain inventive embodiments are mechanically crimped and cut into adesirable fiber length, thereby producing staple fiber. The length ofthe staple fibers typically ranges from 25 to 50 millimeters, althoughthe fibers may be cut to any desired length outside this range.

The multi-component fibers of the invention may be staple fibers,continuous filaments, or meltblown fibers. In general, staple fibers,multifilament, and spunbond fibers formed in accordance with the presentinvention may have a fineness of 0.1 to 500 microns per filament. Inother embodiments, the filaments have a fineness diameter of between 10and 50 microns per filament.

Meltblown filaments can have a fineness of 0.1 to 500 microns.Monofilament fibers may have a fineness of 0.1 to 500 microns. In otherembodiments, the filaments have a fineness diameter or between 10 and 50microns per filament.

The multi-component fibers of the invention are useful in the productionof a wide variety of products, including without limitation nonwovenstructures, such as but not limited to carded webs, wet laid webs, drylaid webs, spunbond webs, meltblown webs, and the like. The nonwovenwebs can be bonded to transform the webs into a coherent nonwoven fabricusing bonding techniques known in the industry. Exemplary bondingtechniques for nonwoven webs include mechanical bonding, such ashydro-entanglement and needle punching, adhesive bonding, thermalbonding, and the like. An example of thermal bonding is through airbonding, although other thermal bonding techniques, such as calendaring,microwave, or other RF treatments are readily employed.

An inventive fiber is well suited for use in a composite product, suchas one with a dual surface in which a melt blown web includes a surfacelayer of fibers applied on the surface of the web to create a differenttextured surface relative to the web. By way of example, a polypropyleneweb with the detectable inventive particle filled fiber for the texturedside. A composite example has a spun bond melt blown spun bond (SMS)where only one layer has the inventive detectable fibers. SMS is a verycommon composite nonwoven used in surgical gowns.

Articles formed according to the present invention from such particulateloaded fibers illustratively include non-limiting example of hair nets,protective suits, shoe covers, wipes, food packaging, aprons, beardcovers, and mop heads. Such products in certain embodiments retain theoperational properties of non-particulate loaded fibers of the samepolymer composition, with the added attribute of being detectable withconventional food, medical and pharmaceutical production magnetic orX-ray detectors.

In some inventive embodiments, the inventive fibers are subjected to acoating, laminate, or otherwise cover the outer and/or inner surfaces ofthreads or layers of material contained within any final product withoutfalling outside the scope of the invention. This is a practice wellknown to those experienced in the art, and is commonly used to impartnon-stick, low-friction, or additional chemical and heat resistanceproperties to the final product. However, additional non-polymericparticles identical, similar, or fundamentally different to theparticles already contained within the composite fibers of theinvention, yet at the expense of lowering the overall metal contentloading of the resultant article unless such treatments carry therewithparticulate.

In certain embodiments of the present invention a fiber or core portionof a sheathed fiber has particulate protruding from the wall of thefiber and a concomitant relative depletion of particulate from thecentral region of a fiber. The inclusion of particulate protrusions anda centrally depleted fiber region has been found to afford considerablebenefits in increasing the loading amount of particulate to detectablelevels and the energy needed to slide fibers past one another.

In some embodiments of the present invention, following extrusion butprior to coating or lamination, the fibers or other non-woven creationsof the invention are coated, dusted, or otherwise induced to carry onthe exterior of individual filaments or layers additional particulateidentical, similar, or fundamentally different to the particulatealready contained within the composite fibers of the invention.

Particulate is most easily adhered to the outside of the fibers using aprocess which passes the extruded filament or non-woven creation throughan enclosed chamber or fluidized bed, in which a fan system lifts andcirculates the particulate throughout the air contained within thechamber such that a fraction of the particles that contact the filamentwill adhere to the surface.

In another embodiment of the invention, the fibers of the invention areused to make yarns. Yarns prepared for use in forming such woven andknit fabrics are similarly included within the scope of the presentinvention. Such yarns may be prepared from the continuous filament orspun yarns comprising staple fibers of the present invention by methodsknown in the industry, such as twisting or air entanglement.

An inventive non-woven fabric performs comparably to standard polymercontaining fabrics with respect to most attributes, such as strength,durability, and hand, yet like the fibers exhibits properties whichdeviate significantly from those normally associated with the polymericmaterial by those experienced in the art, these unique properties besidedetectability illustratively include high density, conductivity,electromagnetic shielding, cut-resistance, heat-resistance, andradiation shielding relative to the base polymer absent particulateloading.

The fibers or filament produced by this invention are suitable forapplication in knitting yarns. Further detail is outside the scope ofthis invention, but is well known to those experienced in the art. Onceformed, the fabric may be cut, sewn, and otherwise tailored towards itsfinal purpose using techniques also known to those skilled in the art.Furthermore, the fabric of the present invention may be manufactured,tailored, or otherwise altered or modified in design to exhibit otherfunctional properties without falling outside the scope of theinvention. These alterations or modifications illustratively includemicro-perforations, patches of alternative fabrics, seamless knitting,fashion-centric alterations, dyeing or other coloring, and snaps,zippers, or other pockets for the addition and removal of personaleffects, weights, or other articles to be carried or worn.

Additionally, the fabric of the present invention may be formed using avariety of different weaving or knitting techniques, both those knownand unknown to those experienced in the art, without falling outside thescope of the present invention, which may result in additional qualitiesor properties of the final product. For example, processes and machineryhave been developed to knit at very high speeds, at very low amounts ofstress on the fiber or fabric, and in seamless and/or circular patternsand arrangements.

Additionally, the fabric of the present invention may be used toconfigure composite articles, both those known and unknown to thoseexperienced in the art, without falling outside the scope of the presentinvention, which may result in additional qualities or properties of thefinal product. For example, processes and machinery have been developedto mechanically integrate microfiber thread loops into the detectableground fabric to produce stitchbonded microfiber napped wipes.

Modern metal detection is based on creating a magnetic field with atransmitter coil and two receiving coils wired in reverse. The resultingfield is interrupted when a conductive or magnetic contaminant passesthrough the field. The contaminant is detected by measuring the changein voltage above the change in voltage of non-contaminated product. If acontaminant is detected, that product is rejected. Contaminants aregenerally categorized as sphere equivalents in millimeters. Thesensitivity and throughput of the contaminant detection process ismachine dependent.

X-ray inspection is based on density. The higher the density of theobject being examined, the more energy is absorbed. X-ray detectionmeasures how much energy is absorbed by a product or contaminant. X-raydetection can detect contaminants such as glass or bone that a metaldetector will not detect. X-ray detection can perform other qualityfunctions outside the scope of process or product contamination. Thepresent invention focuses on contaminant and foreign object detection.The sensitivity and throughput of an X-ray inspection process is alsomachine dependent.

The following are specific non-limiting examples of embodiments of thepresent invention. These examples should not be considered to be a limiton the scope of the appended claims.

Example 1

Spherical stainless steel particulate (430 series) having a Poisson sizedistribution and an average particle size of 12 microns is mixed intopolypropylene (PP) to form pellets with a particulate loading of 12percent. The particles are melt-spun by running through a five layerscreen pack of mesh sized from 30 to 325. The melt is then drawn to afiber as shown in FIGS. 1B-1C. Some of the particulate is noted to beflattened or misshaped.

Example 2

Spun fiber PP with BaSO₄. The fiber is spun into pads as shown in FIGS.2A-2H. The resulting fibers are detectable with X-rays when layers ofspun fiber pads are overlayed and imaged by transmitted X-rays.Photograph of extruded polypropylene fiber containing 30.0 wt % bariumsulfate particles (FIG. 2A), X-ray film of extruded polypropylene fibercontaining 30.0 wt % barium sulfate particles (FIG. 2B), photograph ofpad cut from melt-blown polypropylene fiber containing 30.0 wt % bariumsulfate particles (FIG. 2C), X-ray film of pad cut from melt-blownpolypropylene fiber containing 30.0 wt % barium sulfate particles (FIG.2D), X-ray transmission images of barium sulfate/propylene melt-blownpads clockwise from the first quadrant for 3, 6, 20, and 10 layers thatare produced with higher die temperature to yield a comparatively denserpad, as compared to those of FIG. 2F (FIG. 2E), X-ray transmissionimages of barium sulfate/propylene melt-blown pads clockwise from thefirst quadrant for 3, 6, 20, and 10 layers that are produced with lowerdie temperature to yield a fluffier pad (FIG. 2F), X-ray transmissionimage of barium sulfate/propylene melt-blown as a 10 layer pad submergedin 3.5 inches of water to simulate tissue with a US quarter used as aweight to keep the pad submerged (FIG. 2G), and X-ray transmission imageof barium sulfate/propylene melt-blown as a 20 layer pad submerged in3.5 inches of water to simulate tissue with two US quarters used as aweight to keep the pad submerged (FIG. 2H).

Example 3

Spun fiber PP with BaSO₄ and gold nanocrystals. The process of Example 2is repeated with cooled fibers drawn through a suspension of 3 nm goldnanocrystals prior to take up on a godet roller to obtain a 0.1 totalweight percent gold nanocrystal coating fiber that is formed into a padper Example 2. The resulting pad covalently bonds thiols from a testsolution.

Example 4

Spun fiber PP with BaSO₄ and anti-mouse IgG-gold nanocrystals. Theprocess of Example 3 is repeated with cooled fibers drawn through asuspension of commercially available 9-11 nm gold nanocrystals bonded toanti-mouse IgG prior to take up on a godet roller to obtain a 0.05 totalweight percent gold nanocrystal coating fiber that is formed into a padper Example 2. The resulting pad covalently bonds mouse IgG from a testsolution, based on secondary labelling of the IgG.

Example 5

Spun fiber PP with BaSO₄ and gold nanocrystals. The pad of Example 3 iscompressed in a test tube and exposed to a buffer solution of 0.3 M NaCland 10 mM phosphate buffer containing dithiothreitol or mercaptoethanol,(0.1 ml, 100 mM) at 40° C. for 30 minutes to fix the shape of the pad tothat of the test tube, after removal therefrom.

The foregoing description is illustrative of particular embodiments ofthe invention, but is not meant to be a limitation upon the practicethereof. The following claims, including all equivalents thereof, areintended to define the scope of the invention.

The invention claimed is:
 1. A non-woven fiber article for use in a foodproduction, a medical production, or a pharmaceutical productionenvironment, said article comprising: a melt-spun thermoplastic polymerfiber having a cross-section and a length; and a deformed stainlesssteel detectable particulate distributed in the melt-spun thermoplasticpolymer fiber, the stainless steel detectable particle having a size ofless than 31 microns to render the thermoplastic polymer fiberdetectable, alone or in combination with a secondary functionalparticulate distributed in or on the polymer fiber to render thethermoplastic polymer fiber chemically responsive to a chemicalreactant, change in pH or temperature; wherein said stainless steeldetectable particulate comprises a plurality of spherical particles, anda plurality of flattened and misshaped particles formed from sphericalparticles, said particulate distributed in said thermoplastic polymer,wherein said particulate is present from 2 to 12 total weight percent ofthe total weight of the fiber; wherein said stainless steel detectableparticulate is detectable by X-ray detection or magnetic detection; andwherein said melt-spun thermoplastic polymer fiber combined with saiddeformed stainless steel detectable particulate and said secondaryfunctional particulate when present has a weight per unit length of 2.0denier and the article defining a shape of a hair net, a protectivesuit, a shoe cover, a wipe, packaging, an apron, a beard cover, or a mophead.
 2. The article of claim 1 wherein the stainless steel detectableparticulate having a shortest linear dimension as measured from amongthree orthogonal Cartesian coordinate axes X-Y-Z that is less than orequal to one half a cross-sectional average dimension of the polymerfiber along the three orthogonal Cartesian coordinate axes X-Y-Z.
 3. Thearticle of claim 1 wherein the thermoplastic polymer fiber is one ofpolypropylene, polyethylene, polybutene, polyisobutylene, a polyamide, apolyacrylate, a polystyrene, a polyurethane, an acetal resins, apolyethylene vinyl alcohol; a polyester, a polyphenylene sulfide, athermoplastic elastomers, a polyacrylonitrile; a cellulose, apolyaramid, or a block copolymer containing at least one of theaforementioned.
 4. The article of claim 1 wherein the thermoplasticpolymer fiber is a single composition with the cross section that is oneof circular, multi-lobal or polygonal.
 5. The article of claim 1 furthercomprising a sheath surrounding the thermoplastic polymer fiber.
 6. Thearticle of claim 5 further comprising a particulate loaded dustingintermediate between said thermoplastic polymer fiber and said sheath.7. The article of claim 1 wherein said polymer fiber has a diameterbetween 0.1 and 500 microns.
 8. The article of claim 1 wherein thesecondary functional particulate comprises a metallic nanocrystal. 9.The article of claim 1 wherein the secondary functional particulate ispresent from 0.01 to 5 total weight percent of the melt-spun polymerfiber.
 10. The article of claim 1 wherein the secondary functionalparticulate comprises a gold nanocrystal.
 11. The article of claim 10further comprising a moiety covalently bonded to the gold nanocrystal.12. A process of detecting a fabric article comprising: forming athermoplastic polymer fiber having a cross-section and a length and adetectable particulate distributed in the thermoplastic polymer fiber,wherein the detectable particulate is a deformed stainless steeldetectable particulate distributed in the thermoplastic polymer fiber,the stainless steel detectable particle having a size of less than 31microns to render the thermoplastic polymer fiber detectable, alone orin combination with a secondary functional particulate distributed in oron the polymer fiber to render the thermoplastic polymer fiberchemically responsive to a chemical reactant, change in pH ortemperature, wherein said stainless steel detectable particulatecomprises a plurality of spherical particles and a plurality offlattened and misshaped particles formed from spherical particles, saiddetectable particulate distributed in said thermoplastic polymer,wherein said particulate is present from 2 to 12 total weight percent ofthe total weight of the thermoplastic polymer fiber, wherein saidstainless steel detectable particulate is detectable by X-ray detectionor magnetic detection, and wherein said thermoplastic polymer fibercombined with said deformed stainless steel detectable particulate andsaid secondary functional particulate when present has a weight per unitlength of 2.0 denier; forming a fabric at least partially from saidthermoplastic polymer fiber; manufacturing the fabric article at leastpartially from said fabric; passing the fabric article through an X-raydetector or a magnetic detector; and collecting a signal from said X-raydetector or magnetic detector indicative of the presence of the fabricarticle.
 13. The process of detecting the fabric article of claim 12wherein the fabric article is a medical device.
 14. The process ofdetecting the fabric article of claim 12 wherein the fabric article isnon-woven.